Chapter 24 Java Management Extensions JMX Outline 24

Chapter 24 – Java Management Extensions (JMX) Outline 24. 1 Introduction 24. 2 Installation 24. 3 Case Study 24. 3. 1 Instrument Resources 24. 3. 2 Implement the JMX Management Agent 24. 3. 3 Broadcasting and Receiving Notifications 24. 3. 4 Management Application 24. 3. 5 Compiling and Running the example 24. 4 Internet and World Wide Web Resources 2001 Prentice Hall, Inc. All rights reserved.

24. 1 Introduction • Network management problems • Current network management solutions – agents • Recent technological advances • JMX – Three-level management architecture • Instrumentation level • Agent level • Management level 2001 Prentice Hall, Inc. All rights reserved.

24. 1 Introduction • JMX provides – – – Platform-independence Protocol-independence Reusable Intelligent agent Scalability 2001 Prentice Hall, Inc. All rights reserved.

24. 1 Introduction Manager Level Agent Level Instrumentation Level 2001 Prentice Hall, Inc. All rights reserved. Management Application Java Dynamic Management Agent Managed Resource

24. 2 Installation • Implementation of JMX – Java Dynamic Management Kit (JDMK) • Download JDMK – www. sun. com/software/java-dynamic/try. html • Set CLASSPATH – jdmkrt. jar and jdmktk. jar 2001 Prentice Hall, Inc. All rights reserved.

24. 3 Case Study • Management solution – Resource – Agent – Application • MBean server 2001 Prentice Hall, Inc. All rights reserved.

24. 3 Case Study Management Application Rmi. Connector. Client: 5555 Rmi. Connector. Server: 5555 MBean. Server Printer MBean Printer. Simulator 2001 Prentice Hall, Inc. All rights reserved. Printer. Event. Broadcaster MBean

24. 3. 1 Instrument Resources • Instrument a resource – Standard MBean • MBean interface • MBean class • MBean interface design pattern – – – Naming Expose attributes of a management interface Methods Operations Serializable 2001 Prentice Hall, Inc. All rights reserved.

24. 3. 1 Instrument Resources • MBean class design pattern – Implement MBean interface – Public and concrete – Public constructor 2001 Prentice Hall, Inc. All rights reserved.

Outline 1 // Fig. 22. 3: Printer. MBean. java 2 // This class specifies the interface that will be implemented 3 // by Printer, which will function as an MBean. 4 5 // deitel package 6 package com. deitel. advjhtp 1. jmx. Printer. Simulator; 7 8 public interface Printer. MBean { 9 10 // is it printing? Interface name 11 public Boolean is. Printing(); 12 with MBean suffix 13 // is it online? 14 public Boolean is. Online(); 15 16 // is paper jammed? Interface 17 public Boolean is. Paper. Jam(); Printer. MBean 18 Management interface 19 // returns paper amount in tray 1. Declarations 20 public Integer get. Paper. Tray(); 21 22 // returns ink level in toner cartridge 23 public Integer get. Toner(); Return value is serializable 24 25 // returns ID of print job that is currently printing 26 public String get. Current. Print. Job(); 27 28 // returns array of all queued up print jobs is, get, set 29 public String [] get. Pending. Print. Jobs(); methods 30 31 // sets availability status of printer 32 public void set. Online ( Boolean online ); 33 2001 Prentice Hall, Inc. All rights reserved.

Outline 34 // fills up paper tray again with paper 35 public void replenish. Paper. Tray(); 36 37 // cancel pending print jobs 38 public void cancel. Pending. Print. Jobs(); 39 40 // start printing process 41 public void start. Printing(); 42 } 1 // Fig. 22. 4: Printer. Event. Listener. java 2 // The listener interface for printer events. 3 4 // Deitel package 5 package com. deitel. advjhtp 1. jmx. Printer; 6 7 public interface Printer. Event. Listener { 8 9 public void out. Of. Paper(); 10 11 public void low. Toner(); 12 13 public void paper. Jam(); 14 } operations Interface Printer. Event. Listener 2001 Prentice Hall, Inc. All rights reserved.

Outline 1 // Fig. 22. 5: Printer. java 2 // This class provides implementation for Printer. MBean 3 // interface and registers a managing MBean for the Printer 4 // device, which is simulated by Printer. Simulator. java. 5 6 // deitel package 7 package com. deitel. advjhtp 1. jmx. Printer. Simulator; 8 9 // Java core package 10 import java. lang. Thread; 11 import java. util. Array. List; 12 13 // JMX core packages 14 import javax. management. *; Class 15 Printer 16 // Deitel packages 17 import com. deitel. advjhtp 1. jmx. Printer. *; 1. Declarations 18 19 public class Printer implements Printer. MBean, 2. Constructor 20 Printer. Event. Listener { MBean class implements 21 responding MBean interface 2. 1 connect to 22 private Printer. Simulator printer. Simulator ; printer device 23 private static final int PAPER_STACK_SIZE = 50; 24 private Object. Instance event. Broadcaster. Instance ; 25 private Object. Name event. Broadcaster. Name ; 26 private Object. Name printer. Name; 27 private MBean. Server m. Bean. Server ; 28 Connect to 29 public Printer() Public constructor 30 { printer device 31 // connect to the printer device 32 printer. Simulator = new Printer. Simulator( this ) ; 33 Thread my. Thread = new Thread( printer. Simulator ) ; 34 my. Thread. start(); 2001 Prentice Hall, Inc. 35 All rights reserved.

36 // find all MBean servers in current JVM Find MBean 37 Array. List array. List = 38 MBean. Server. Factory. find. MBean. Server( null ); servers 39 40 // retrieve the MBean. Server reference 41 if ( array. List. size() == 0) 42 System. out. println( "Cannot find a MBean. Server!" ); 43 44 else { 45 46 // get the MBean. Server that has the 47 // Printer. Event. Broadcaster MBean registered with it 48 for ( int i = 0; i < array. List. size(); i++ ) { 49 MBean. Server found. MBean. Server = 50 ( MBean. Server )array. List. get( i ); 2. 2 find MBean servers 51 Specify MBean 52 // obtain the object name for the 2. 3 specify MBean 53 // Printer. Event. Broadcaster MBean server requirement 54 try { requirement 55 String name = found. MBean. Server. get. Default. Domain() 2. 4 identify MBean 56 + ": type=" + "Printer. Event. Broadcaster"; server 57 event. Broadcaster. Name = new Object. Name( name ); 58 } 59 60 // handle exception when creating Object. Name 61 catch ( Malformed. Object. Name. Exception exception ) { 62 exception. print. Stack. Trace(); 63 } 64 65 // check whether the Printer. Event. Broadcaster MBean is 66 // registered with this MBean. Server 67 if ( found. MBean. Server. is. Registered( Identify MBean server 68 event. Broadcaster. Name ) ) { 69 m. Bean. Server = found. MBean. Server; 2001 Prentice Hall, Inc. 70 break; All rights reserved. 71 } Outline

72 73 } // end for loop 74 75 } // end if-else to get the MBean. Server reference 76 77 } // end Printer. Simulator constructor 78 79 // will stop the printer thread from executing 80 // once execution should stop. 81 public void stop() 82 { 83 printer. Simulator. stop(); 84 } 85 86 // Is it printing? 87 public Boolean is. Printing() 88 { 89 return new Boolean( printer. Simulator. is. Printing() ); 90 } 91 92 // is online? 93 public Boolean is. Online() 94 { 95 return printer. Simulator. is. Online(); 96 } 97 98 // is paper jammed? 99 public Boolean is. Paper. Jam() 100 { 101 return printer. Simulator. is. Paper. Jam(); 102 } 103 104 // is paper tray empty? 105 public Integer get. Paper. Tray() 106 { 107 return printer. Simulator. get. Paper. Tray(); 108 } Outline 3. Implement management solution 2001 Prentice Hall, Inc. All rights reserved.

109 110 // is toner low? 111 public Integer get. Toner() 112 { 113 return printer. Simulator. get. Toner(); 114 } 115 116 // returns ID of print job that is currently printing 117 public String get. Current. Print. Job() 118 { 119 return printer. Simulator. get. Current. Print. Job(); 120 } 121 122 // returns array of all queued up print jobs 123 public String[] get. Pending. Print. Jobs() 124 { 125 return printer. Simulator. get. Pending. Print. Jobs(); 126 } 127 128 // sets status availability of printer 129 public void set. Online( Boolean online ) 130 { 131 if ( online. boolean. Value() == true ) 132 printer. Simulator. set. Online(); 133 else 134 printer. Simulator. set. Offline(); 135 } 136 137 // fills up the paper tray again with paper. 138 public void replenish. Paper. Tray() 139 { 140 printer. Simulator. replenish. Paper. Tray ( 141 Printer. PAPER_STACK_SIZE ); 142 } 143 Outline 3. Implement management solution 2001 Prentice Hall, Inc. All rights reserved.

144 // cancel pending print jobs 145 public void cancel. Pending. Print. Jobs() 146 { 147 printer. Simulator. cancel. Pending. Print. Jobs(); 148 } 149 150 // start the printing process 151 public void start. Printing() 152 { 153 printer. Simulator. start. Printing. Process(); 154 } 155 156 // send out of paper event to JMX layer 157 public void fire. Out. Of. Paper. Event() 158 { Specify 159 // construct parameters and signatures 160 Object[] parameter = new Object[ 1 ]; 161 parameter[ 0 ] = new Notification( 162 "Printer. Event. OUT_OF_PAPER", this, 0 L ); 163 String[] signature = new String[ 1 ]; 164 signature[ 0 ] = "javax. management. Notification" ; 165 166 // invoke notification 167 try { 168 m. Bean. Server. invoke( event. Broadcaster. Name, 169 "send. Notification", parameter, signature ); 170 } 171 172 // handle exception when invoking method 173 catch ( Reflection. Exception exception ) { 174 exception. print. Stack. Trace(); 175 } 176 Outline 4. Send out-of-paper notification 4. 1 specify notification 4. 2 send notification Send notification 2001 Prentice Hall, Inc. All rights reserved.

177 // handle exception when communicating with MBean 178 catch ( MBean. Exception exception ) { 179 exception. print. Stack. Trace(); 180 } 181 182 // handle exception if MBean not found 183 catch ( Instance. Not. Found. Exception exception ) { 184 exception. print. Stack. Trace(); 185 } 186 187 } // end method out. Of. Paper. Event 188 189 // send low toner event to JMX layer 190 public void fire. Low. Toner. Event() 191 { 192 // construct parameters and signatures 193 Object[] parameter = new Object[ 1 ]; 194 parameter[ 0 ] = new Notification( 195 "Printer. Event. LOW_TONER", this, 0 L ); 196 String[] signature = new String[ 1 ]; 197 signature[ 0 ] = "javax. management. Notification" ; 198 199 // invoke notification 200 try { 201 m. Bean. Server. invoke( event. Broadcaster. Name, 202 "send. Notification", parameter, signature ); 203 } 204 205 // handle exception when invoking method 206 catch ( Reflection. Exception exception ) { 207 exception. print. Stack. Trace(); 208 } 209 Outline Specify 5. Send low-toner notification 5. 1 specify notification 5. 2 send notification Send notification 2001 Prentice Hall, Inc. All rights reserved.

210 // handle exception communicating with MBean 211 catch ( MBean. Exception exception ) { 212 exception. print. Stack. Trace(); 213 } 214 215 // handle exception if MBean not found 216 catch ( Instance. Not. Found. Exception exception ) { 217 exception. print. Stack. Trace(); 218 } 219 220 } // end method low. Toner. Event 221 222 // send paper jam event to JMX layer 223 public void fire. Paper. Jam. Event() 224 { 225 // construct parameters and signatures 226 Object[] parameter = new Object[ 1 ]; 227 parameter[ 0 ] = new Notification( 228 "Printer. Event. PAPER_JAM", this, 0 L ); 229 String[] signature = new String[ 1 ]; 230 signature[ 0 ] = "javax. management. Notification" ; 231 232 // invoke notification 233 try { 234 m. Bean. Server. invoke( event. Broadcaster. Name, 235 "send. Notification", parameter, signature ); 236 } 237 238 // handle exception when invoking method 239 catch( Reflection. Exception exception ) { 240 exception. print. Stack. Trace(); 241 } 242 Outline 6. Send paper-jam notification Specify notification 6. 1 specify notification Send notification 2001 Prentice Hall, Inc. All rights reserved.

243 // handle exception communicating with MBean 244 catch( MBean. Exception exception ) { 245 exception. print. Stack. Trace(); 246 } 247 248 // handle exception if MBean not found 249 catch( Instance. Not. Found. Exception exception ) { 250 exception. print. Stack. Trace(); 251 } 252 253 } // end method paper. Jam. Event 254 255 // interface implementation 256 public void out. Of. Paper() 257 { 258 // delegate call 259 fire. Out. Of. Paper. Event (); 260 } 261 262 // interface implementation Interface 263 public void low. Toner() 264 { 265 // delegate call 266 fire. Low. Toner. Event(); 267 } 268 269 // interface implementation 270 public void paper. Jam() 271 { 272 // delegate call 273 fire. Paper. Jam. Event(); 274 } 275 } Outline 6. 2 send notification implementation 2001 Prentice Hall, Inc. All rights reserved.

Outline 1 // Fig. 22. 6: Printer. Simulator. java 2 // This class simulates a printer device on a network. 3 4 // Deitel package 5 package com. deitel. advjhtp 1. jmx. Printer; 6 7 // java core package 8 import java. util. Stack; 9 10 public class Printer. Simulator implements Runnable { 11 12 private Stack printer. Stack = new Stack(); 13 private boolean is. Online = true; 14 private boolean is. Printing = false; Class 15 private boolean is. Paper. Jam = false; Printer. Simulator 16 17 // 50 sheets of paper in tray 1. Declarations 18 private Integer paper. In. Tray = new Integer( 50 ); 19 2. Constructor 20 // 100% full of ink 21 private Integer toner. Cartridge = new Integer( 100 ); 22 23 private String current. Print. Job; 24 private boolean is. Alive = true; 25 private Printer. Event. Listener event. Listener ; 26 27 // default public constructor 28 public Printer. Simulator( Constructor takes 29 Printer. Event. Listener listener ) Printer. Event. Listener 30 { as input 31 event. Listener = listener; 32 } 33 2001 Prentice Hall, Inc. All rights reserved.

34 // stops execution of thread 35 public void stop() 36 { 37 is. Alive = false; 38 } 39 40 // main life-cycle of the printer. 41 // prints one job from print job stack 42 // 1) if offline, it pauses and waits. 43 // 2) if online, handles one print job 44 public void run() 45 { 46 // main loop within thread 47 while ( is. Alive ) { 48 49 // pause if offline 50 if ( !is. Online ) { 51 synchronized ( this ) { 52 53 // waits for printer become online 54 try { 55 wait(); 56 } 57 58 // if interrupt occurs 59 catch ( Interrupted. Exception exception ) { 60 exception. print. Stack. Trace(); 61 System. exit( -1 ); 62 } 63 64 } // end synchronized 65 66 } // end if 67 Outline 3. Simulate printer activities 2001 Prentice Hall, Inc. All rights reserved.

Outline 68 // prints one job from print job stack 69 start. Printing. Process (); 70 71 } // end while 72 } 73 74 public void start. Printing. Process() 75 { 76 // warm up the printer, print top print job from print 77 // stack and adjust paper values and toner values 78 try { 79 // warm up printer for incoming batch of print jobs 80 Thread. sleep( 1000 * 5 ); 81 82 if ( ( paper. In. Tray. int. Value() > 0 ) && 83 ( toner. Cartridge. int. Value() > 10 ) && 84 ( !is. Paper. Jam ) ) { Simulate printing process 85 3. Simulate printer 86 // start the printing process activities 87 current. Print. Job = get. Next. Print. Job(); 88 is. Printing = true; 89 90 // 12 seconds to print a normal document 91 Thread. sleep( 1000 * 12 ); 92 93 // each print job uses 10 pages 94 update. Paper. In. Tray ( paper. In. Tray. int. Value() - 10 ); 95 update. Toner(); 96 update. Paper. Jam (); 97 is. Printing = false; 98 99 // make sure no references are left dangling 100 current. Print. Job = null; 101 } 2001 Prentice Hall, Inc. 102 } All rights reserved.

103 104 // if interrupt occurs 105 catch ( Interrupted. Exception exception ) { 106 exception. print. Stack. Trace(); 107 System. exit( -1 ); 108 } 109 110 } // end method start. Printing. Process 111 112 // returns current printed job 113 public String get. Current. Print. Job() 114 { 115 return current. Print. Job; 116 } 117 118 // is printer online? 119 public Boolean is. Online() 120 { 121 return new Boolean ( is. Online ); 122 } 123 124 // update amount of paper in paper tray 125 public synchronized void update. Paper. In. Tray( int new. Value ) 126 { 127 paper. In. Tray = new Integer ( new. Value ); 128 Add 129 // fire event if paper tray low 130 if ( paper. In. Tray. int. Value() <= 0 ) { 131 event. Listener. out. Of. Paper. Event(); 132 } 133 } 134 135 // is paper jammed? 136 public Boolean is. Paper. Jam() 137 { 138 return new Boolean( is. Paper. Jam ); 139 } Outline 3. Simulate printer activities paper to paper tray 2001 Prentice Hall, Inc. All rights reserved.

140 141 // cancel pending print jobs 142 public void cancel. Pending. Print. Jobs() 143 { 144 synchronized ( printer. Stack ) { 145 printer. Stack. clear(); 146 } 147 } 148 149 // update amount of toner available in toner cartridge 150 public synchronized void update. Toner() 151 { 152 // after every print job, toner levels drop 1% 153 toner. Cartridge = new Integer ( 154 toner. Cartridge. int. Value() - 1 ); 155 156 // fire event if toner is low Update toner in 157 if ( toner. Cartridge. int. Value() <= 10 ) { toner cartridge 3. Simulate printer 158 event. Listener. low. Toner. Event(); activities 159 } 160 } 161 162 public synchronized void update. Paper. Jam() 163 { 164 if ( Math. random() > 0. 9 ) { Issue paper jam 165 is. Paper. Jam = true; 166 event. Listener. paper. Jam. Event(); event randomly 167 } 168 } 169 170 // returns number of pages in paper tray 171 public synchronized Integer get. Paper. Tray() 172 { 173 return paper. In. Tray; 174 } 2001 Prentice Hall, Inc. 175 All rights reserved. Outline

Outline 176 // returns amount of toner in toner cartridge 177 public synchronized Integer get. Toner() 178 { 179 return toner. Cartridge; 180 } 181 182 // generates a random number of print jobs with varying IDs 183 public void populate. Print. Stack() 184 { 185 int num. Of. Jobs = ( int ) ( Math. random ( ) * 10 ) + 1; 186 187 // generate print jobs 188 synchronized ( printer. Stack ) { Generate print jobs 189 for ( int i = 0 ; i < num. Of. Jobs ; i++ ) { 190 printer. Stack. add ( "PRINT_JOB_ID #" + i ); 191 } 3. Simulate printer 192 } activities 193 } 194 195 // returns next print job in stack, populating the stack 196 // if it is empty 197 public String get. Next. Print. Job() 198 { 199 if ( printer. Stack. is. Empty() ) { 200 populate. Print. Stack ( ); 201 202 // simulates absence of print jobs 203 try { 204 Thread. sleep ( 205 ( int ) ( Math. random() * 1000 * 10 ) ); 206 } 207 2001 Prentice Hall, Inc. All rights reserved.

208 // if interrupt occurs 209 catch ( Interrupted. Exception exception ) { 210 exception. print. Stack. Trace() ; 211 System. exit ( -1 ) ; 212 } 213 } 214 215 // Remove topmost queued resource. 216 String print. Job; 217 218 synchronized ( printer. Stack ) { 219 print. Job = ( String ) printer. Stack. pop(); 220 } 221 222 return print. Job; 223 224 } // end method get. Next. Print. Job 225 226 // returns all jobs yet to be printed 227 public String[] get. Pending. Print. Jobs() 228 { 229 String[] pending. Print. Jobs; 230 Get 231 // create array of pending print jobs 232 synchronized ( printer. Stack ) { 233 Object[] temp = printer. Stack. to. Array() ; 234 pending. Print. Jobs = new String[ temp. length ] ; 235 236 for ( int i = 0 ; i < pending. Print. Jobs. length ; i++ ) { 237 pending. Print. Jobs [ i ] = ( String )temp[ i ]; 238 } 239 } 240 241 return pending. Print. Jobs; 242 243 } // end method get. Pending. Print. Jobs Outline 3. Simulate printer activities all jobs to be printed 2001 Prentice Hall, Inc. All rights reserved.

Outline 244 245 // sets printer status to online 246 public void set. Online() 247 { 248 is. Online = true; 249 250 // notify all waiting states 251 synchronized ( this ) { 252 notify. All() ; When printer becomes online, 253 } notify all waiting states 254 } 255 256 // sets printer status to offline 257 public void set. Offline() 258 { 3. Simulate printer 259 is. Online = false; activities 260 } 261 262 // replenishes amount of paper in paper tray to specified 263 // value 264 public void replenish. Paper. Tray ( int paper. Stack ) 265 { 266 update. Paper. In. Tray( paper. Stack ) ; 267 } 268 269 // is printer printing? 270 public boolean is. Printing() 271 { 272 return is. Printing; 273 } 274 } 2001 Prentice Hall, Inc. All rights reserved.

24. 3. 2 Implementation of the JMX Management Agent • JMX agent – MBean server – MBeans (managed resource) – Protocol adaptor or connector 2001 Prentice Hall, Inc. All rights reserved.

1 // Fig. 22. 8: Printer. Management. Agent. java 2 // This application creates an MBean. Server and starts an RMI 3 // connector MBean service. 4 5 // deitel package 6 package com. deitel. advjhtp 1. jmx. Printer. Management; 7 8 // JMX core packages 9 import javax. management. *; 10 11 public class Printer. Management. Agent { 12 13 public static void main( String[] args ) Class 14 { Printer. Management. Agent 15 Object. Instance rmi. Connector. Server = null; 16 Object. Instance printer = null; 1. main 17 Object. Instance broadcaster = null; 18 Object. Name object. Name = null; 1. 1 create MBean. Server 19 20 // create an MBean. Server Create MBean server 1. 2 create RMI 21 MBean. Server server = connector server 22 MBean. Server. Factory. create. MBean. Server(); 23 1. 3 create broadcaster 24 // create an RMI connector service, a printer simulator MBean 25 // MBean and a broadcaster MBean 26 try { 27 Create RMI connector server 28 // create an RMI connector server 29 rmi. Connector. Server = server. create. MBean ( 30 "com. sun. jdmk. comm. Rmi. Connector. Server", null ); 31 32 // create a broadcaster MBean Create broaddcaster MBean 33 String name = server. get. Default. Domain() 34 + ": type=" + "Printer. Event. Broadcaster"; 35 String class. Name = "com. deitel. advjhtp 1. jmx. " 2001 Prentice Hall, Inc. 36 + "Printer. Simulator. Printer. Event. Broadcaster" All rights reserved. Outline

37 38 object. Name = new Object. Name( name ); 39 printer = server. create. MBean( 40 class. Name, object. Name ); 41 42 // create a printer simulator MBean 43 name = server. get. Default. Domain() 44 + ": type=" + "Printer"; 45 class. Name = "com. deitel. advjhtp 1. jmx. " 46 + "Printer. Simulator. Printer"; 47 48 object. Name = new Object. Name( name ); 49 broadcaster = server. create. MBean( 50 class. Name, object. Name ); 51 52 } // end try 53 54 // handle class not JMX-compliant MBean exception 55 catch ( Not. Compliant. MBean. Exception exception ) { 56 exception. print. Stack. Trace(); 57 } 58 59 // handle MBean constructor exception 60 catch ( MBean. Exception exception ) { 61 exception. print. Stack. Trace(); 62 } 63 64 // handle MBean already exists exception 65 catch ( Instance. Already. Exists. Exception exception ) { 66 exception. print. Stack. Trace(); 67 } 68 69 // handle MBean constructor exception 70 catch ( Reflection. Exception exception ) { 71 exception. print. Stack. Trace(); 72 } Outline Create printer simulator MBean 1. 4 create printer simulator MBean 1. 5 handle exceptions 2001 Prentice Hall, Inc. All rights reserved.

73 74 // handle invalid object name exception 75 catch ( Malformed. Object. Name. Exception exception) { 76 exception. print. Stack. Trace(); 77 } Specify RMI 78 connector 79 // set port number server port 80 Object[] parameter = new Object[ 1 ]; 81 parameter[ 0 ] = new Integer( 5555 ); 82 String[] signature = new String[ 1 ]; 83 signature[ 0 ] = "int"; 84 85 // invoke method set. Port on Rmi. Connector. Server MBean 86 // start the RMI connector service 87 try { 88 server. invoke( 89 rmi. Connector. Server. get. Object. Name(), "set. Port", 90 parameter, signature ); 91 server. invoke( 92 rmi. Connector. Server. get. Object. Name(), "start" , 93 new Object[ 0 ], new String[ 0 ] ); 94 } 95 96 // handle exception when executing method 97 catch ( Reflection. Exception exception ) { 98 exception. print. Stack. Trace(); 99 } 100 101 // handle exception communicating with MBean 102 catch ( MBean. Exception exception ) { 103 exception. print. Stack. Trace(); 104 } 105 Outline 1. 6 specify RMI Set RMI connector server port 1. 7 set RMI connector server port Start RMI 1. 8 start RMI connector server 2001 Prentice Hall, Inc. All rights reserved.

Outline 106 // handle exception if MBean not found 107 catch ( Instance. Not. Found. Exception exception ) { 108 exception. print. Stack. Trace(); 109 } 110 111 } // end method main 112 } __________________________________ 1 // Fig. 22. 9: Printer. Event. Broadcaster. MBean. java 2 // This class defines the MBean interface. 3 4 // deitel package 5 package com. deitel. advjhtp 1. jmx. Printer. Simulator; 6 7 // JMX core packages 8 import javax. management. Notification; 9 10 public interface Printer. Event. Broadcaster. MBean { 11 12 public void send. Notification( Notification notification ); 13 } Interface Printer. Event. Broadcaster. MBean 1. Declarations 2001 Prentice Hall, Inc. All rights reserved.

24. 3. 3 Broadcasting and Receiving Notifications • Broadcast notifications – Notification broadcaster MBean • Receive notifications 2001 Prentice Hall, Inc. All rights reserved.

Outline 1 // Fig. 22. 10: Printer. Event. Broadcaster. java 2 // This class defines an MBean that 3 // provides events information. 4 5 // deitel package 6 package com. deitel. advjhtp 1. jmx. Printer. Simulator; 7 8 // JMX core packages 9 import javax. management. MBean. Notification. Info; 10 import javax. management. Notification. Broadcaster. Support ; 11 12 // extends Notification. Broadcaster. Support to adopt its 13 // functionality. 14 public class Printer. Event. Broadcaster 15 extends Notification. Broadcaster. Support 16 implements Printer. Event. Broadcaster. MBean { 17 18 private static final String OUT_OF_PAPER = 19 "Printer. Event. OUT_OF_PAPER"; 20 private static final String LOW_TONER = 21 "Printer. Event. LOW_TONER"; 22 private static final String PAPER_JAM = 23 "Printer. Event. PAPER_JAM"; 24 Class Printer. Event. Broadcaster 1. Declarations 2001 Prentice Hall, Inc. All rights reserved.

Outline 25 // provide information about deliverable events 26 public MBean. Notification. Info[] get. Notification. Info() 27 { 28 // array containing descriptor objects 29 MBean. Notification. Info [] descriptor. Array = 30 new MBean. Notification. Info[ 1 ]; Implement 31 32 // different event types get. Notification. Info 33 String[] notification. Types = new String[ 3 ]; to describe events 34 notification. Types[ 0 ] = 35 Printer. Event. Broadcaster. OUT_OF_PAPER; 36 notification. Types[ 1 ] = 37 Printer. Event. Broadcaster. LOW_TONER; Specify event types 38 notification. Types[ 2 ] = 39 Printer. Event. Broadcaster. PAPER_JAM; 2. Implement 40 get. Notification. Info 41 // notification class type to describe events 42 String class. Type = "javax. management. Notification" ; 43 44 // description of MBean. Notification. Info Event description 45 String description = 46 "Notification types for Printer. Event. Broadcaster "; 47 48 // populate descriptor array 49 descriptor. Array[ 0 ] = new MBean. Notification. Info( 50 notification. Types , class. Type, description ); 51 52 return descriptor. Array; 53 54 } // end method get. Notification. Info 55 } 2001 Prentice Hall, Inc. All rights reserved.

1 // Fig. 22. 11: Printer. Event. Handler. java 2 // The class adds a listener to the broadcaster MBean and 3 // defines the event handlers when event occurs. 4 5 // deitel package 6 package com. deitel. advjhtp 1. jmx. Client; 7 8 // JMX core packages 9 import javax. management. *; 10 11 // JDMK core packages 12 import com. sun. jdmk. comm. Rmi. Connector. Client; 13 import com. sun. jdmk. comm. Client. Notification. Handler ; 14 15 // Deitel packages Class 16 import com. deitel. advjhtp 1. jmx. Printer. *; Printer. Eventhandler 17 18 public class Printer. Event. Handler { 19 1. Inner class 20 private Rmi. Connector. Client rmi. Client ; 21 private Printer. Event. Listener event. Target ; Inner Notification. Listener class 22 Notification. Listener 23 // notification listener annonymous inner class 24 private Notification. Listener notification. Listener = 25 new Notification. Listener() { 26 public void handle. Notification( 27 Notification notification, Object handback ) 28 { 29 // retrieve notification type 30 String notification. Type = notification. get. Type(); 31 32 // handle different notifications 33 if ( notification. Type. equals( 34 "Printer. Event. OUT_OF_PAPER" ) ) { 35 handle. Out. Of. Paper. Event(); 2001 Prentice Hall, Inc. 36 return; All rights reserved. 37 } Outline

39 if ( notification. Type. equals( 40 "Printer. Event. LOW_TONER" ) ) { 41 handle. Low. Toner. Event(); 42 return; 43 } 44 45 if ( notification. Type. equals( 46 "Printer. Event. PAPER_JAM" ) ) { 47 handle. Paper. Jam. Event(); 48 return; 49 } 50 51 } // end method handle. Notification 52 53 }; // end annonymous inner class 2. Constructor 54 55 // default constructor 2. 1 set notification 56 public Printer. Event. Handler( mode 57 Rmi. Connector. Client input. Rmi. Client , 58 Manager. Side. Printer. Event. Listener input. Event. Target ) 2. 2 register listener 59 { to RMI connector 60 rmi. Client = input. Rmi. Client; client 61 event. Target = input. Event. Target; Set notification mode 62 63 // set notification push mode 64 rmi. Client. set. Mode( Client. Notification. Handler. PUSH_MODE ); 65 66 // register listener 67 try { 68 Object. Name object. Name = new Object. Name( Register listener to 69 rmi. Client. get. Default. Domain() RMI connector client 70 + ": type=" + "Printer. Event. Broadcaster" ); 71 72 rmi. Client. add. Notification. Listener( object. Name, 73 notification. Listener, null ); 2001 Prentice Hall, Inc. 74 } All rights reserved. Outline

Outline 75 76 // if MBean does not exist in the MBean server 77 catch ( Instance. Not. Found. Exception exception) { 78 exception. print. Stack. Trace(); 79 } 80 81 // if the format of the object name is wrong 82 catch ( Malformed. Object. Name. Exception exception ) { 83 exception. print. Stack. Trace(); 84 } 85 86 } // end Printer. Event. Handler constructor 87 88 // delegate out of paper event 89 private void handle. Out. Of. Paper. Event() 3. Delegate printer 90 { events 91 event. Target. out. Of. Paper(); 92 } 93 Delegate printer events 94 // delegate low toner event 95 private void handle. Low. Toner. Event() 96 { 97 event. Target. low. Toner(); 98 } 99 100 // delegate paper jam event 101 private void handle. Paper. Jam. Event() 102 { 103 event. Target. paper. Jam(); 104 } 105 } 2001 Prentice Hall, Inc. All rights reserved.

24. 3. 4 Management Application • Management application for the case study – GUI for managing the printer • Client. Printer. Management • Manager. Side. Printer. Event. Listener • Printer. Management. GUI 2001 Prentice Hall, Inc. All rights reserved.

Outline 1 // Fig. 22. 12: Client. Printer. Management. java 2 // This application establishes a connection to the MBean. Server 3 // and creates an MBean for Printer. Simulator. 4 5 // deitel package 6 package com. deitel. advjhtp 1. jmx. Client; 7 8 // Java core packages 9 import java. awt. *; 10 import java. awt. event. *; 11 12 // JMX core packages 13 import javax. management. *; 14 Class 15 // JDMX core packages Client. Printer. Management 16 import com. sun. jdmk. comm. Rmi. Connector. Client; 17 import com. sun. jdmk. comm. Rmi. Connector. Address; 1. Constructor 18 19 public class Client. Printer. Management { 1. 1 get RMI connector 20 client 21 private Rmi. Connector. Client rmi. Client ; 22 23 // instantiate client connection Get RMI connector client 24 public Client. Printer. Management () 25 { 26 // create connector client instance 27 rmi. Client = new Rmi. Connector. Client(); 28 29 // create address instance 30 Rmi. Connector. Address rmi. Address = 31 new Rmi. Connector. Address(); 32 2001 Prentice Hall, Inc. All rights reserved.

Set RMI 33 // specify port 34 rmi. Address. set. Port( 5555 ); client port 35 36 // establish connection Establish 37 rmi. Client. connect( rmi. Address ); 38 connection 39 } // end Clinet. Printer. Management constructor 40 41 // return Rmi. Connector. Client reference 42 public Rmi. Connector. Client get. Client () 43 { 44 return rmi. Client; 45 } 46 47 public static void main( String[] args ) 48 { 49 // instantiate client connection 50 Client. Printer. Management client. Manager = 51 new Client. Printer. Management (); 52 53 // get RMIConnector. Client handle 54 Rmi. Connector. Client client = client. Manager. get. Client(); 55 56 // start GUI 57 Printer. Management. GUI printer. Management. GUI = Invoke 58 new Printer. Management. GUI( client ); 59 60 // display the output 61 printer. Management. GUI. set. Size( 62 new Dimension( 500, 500 ) ); 63 printer. Management. GUI. set. Visible( true ); 64 65 } // end method main 66 } Outline 1. 2 set RMI client port 1. 3 establish connection 2. Get Rmi. Connector. Client reference 3. main 3. 1 invoke constructor GUI 3. 2 invoke GUI 2001 Prentice Hall, Inc. All rights reserved.

1 // Fig. 22. 14: Printer. Management. GUI. java 2 // This class defines the GUI for the 3 // printer management application. 4 5 // deitel package 6 package com. deitel. advjhtp 1. jmx. Client; 7 8 // Java AWT core package 9 import java. awt. *; 10 import java. awt. event. *; 11 12 // Java standard extensions 13 import javax. swing. *; 14 15 // JMX core packages Class 16 import javax. management. *; Printer. Management. GUI 17 18 // JDMX core packages 1. Import packages 19 import com. sun. jdmk. comm. Rmi. Connector. Client; 20 import com. sun. jdmk. comm. Rmi. Connector. Address; 2. Inner class 21 Text. Appender 22 // Deitel packages 23 import com. deitel. advjhtp 1. jmx. Printer. *; 24 25 public class Printer. Management. GUI extends JFrame 26 implements Printer. Event. Listener { 27 28 // Text. Appender appends text to a JText. Area. This Runnable 29 // object should be executed only using Swing. Utilities 30 // methods invoke. Later or invoke. And. Wait as it modifies 31 // a live Swing component. 32 private class Text. Appender implements Runnable { 33 Inner class 34 private String text; Text. Appender 35 private JText. Area text. Area; 2001 Prentice Hall, Inc. 36 All rights reserved. Outline

37 // Text. Appender constructor 38 public Text. Appender( JText. Area area, String new. Text ) 39 { 40 text = new. Text; 41 text. Area = area; 42 } 43 44 // display new text in JText. Area 45 public void run() 46 { 47 // append new message 48 text. Area. append( text ); 49 50 // move caret to end of message. Area to ensure new 51 // message is visible on screen 52 text. Area. set. Caret. Position( 53 text. Area. get. Text(). length() ); 3. Constructor 54 } 55 3. 1 define status 56 } // end Text. Appender inner class panel 57 58 private Object. Name object. Name; 59 private Rmi. Connector. Client client; 60 private JText. Area printer. Status. Text. Area = new JText. Area(); 61 private JText. Area printer. Event. Text. Area = new JText. Area(); 62 63 public Printer. Management. GUI( Rmi. Connector. Client rmi. Client ) 64 { 65 super( "JMX Printer Management Example" ); 66 67 Container container = get. Content. Pane(); Define status 68 panel 69 // status panel 70 JPanel printer. Status. Panel = new JPanel(); 71 printer. Status. Panel. set. Preferred. Size( 2001 Prentice Hall, Inc. 72 new Dimension( 512, 200 ) ); All rights reserved. Outline

73 JScroll. Pane status. Scroll. Pane = new JScroll. Pane(); 74 status. Scroll. Pane. set. Autoscrolls( true ); 75 status. Scroll. Pane. set. Preferred. Size( 76 new Dimension( 400, 150 ) ); 77 status. Scroll. Pane. get. Viewport(). add( 78 printer. Status. Text. Area, null ); 79 printer. Status. Panel. add( status. Scroll. Pane, null ); 80 81 // buttons panel 82 JPanel button. Panel = new JPanel(); 83 button. Panel. set. Preferred. Size( 84 new Dimension( 512, 200 ) ); Define buttons 85 panel 86 // define action for Check Status button 87 JButton check. Status. Button = 88 new JButton( "Check Status" ); 89 check. Status. Button. add. Action. Listener( 3. 2 define buttons 90 panel 91 new Action. Listener() { 92 3. 2. 1 define actions 93 public void action. Performed( Action. Event event ) { for the buttons 94 check. Status. Button. Action( event ); Define actions for 95 } the buttons 96 } 97 ); 98 99 // define action for Add Paper button 100 JButton add. Paper. Button = new JButton( "Add Paper" ); 101 add. Paper. Button. add. Action. Listener( 102 new Action. Listener() { 103 104 public void action. Performed(Action. Event event) { 105 add. Paper. Button. Action( event ); 106 } 107 } 2001 Prentice Hall, Inc. 108 ); All rights reserved. 109 Outline

110 // define action for Cancel Pending Print Jobs button 111 JButton cancel. Pending. Print. Jobs. Button = new JButton( 112 "Cancel Pending Print Jobs" ); 113 cancel. Pending. Print. Jobs. Button. add. Action. Listener( 114 new Action. Listener() { Define actions 115 116 public void action. Performed( Action. Event event ) { for the buttons 117 cancel. Pending. Print. Jobs. Button. Action ( event ); 118 } 119 } 120 ); 121 122 // add three buttons to the panel 123 button. Panel. add( check. Status. Button, null ); 124 button. Panel. add( add. Paper. Button, null ); 125 button. Panel. add( cancel. Pending. Print. Jobs. Button , null ); 126 127 // events panel 128 JPanel printer. Event. Panel = new JPanel(); 129 printer. Event. Panel. set. Preferred. Size( 3. 3 define events Define panel events panel 130 new Dimension( 512, 200) ); 131 JScroll. Pane events. Scroll. Pane = new JScroll. Pane(); 132 events. Scroll. Pane. set. Autoscrolls( true ); 133 events. Scroll. Pane. set. Preferred. Size( 134 new Dimension( 400, 150 ) ); 135 events. Scroll. Pane. get. Viewport(). add( 136 printer. Event. Text. Area, null ); 137 printer. Event. Panel. add( events. Scroll. Pane, null ); 138 139 // initialize the text 140 printer. Status. Text. Area. set. Text( "Printer Status: ---n" ); 141 printer. Event. Text. Area. set. Text( "Events: --- n" ); 142 143 // put all the panels together 144 container. add( printer. Status. Panel, Border. Layout. NORTH ); 2001 Prentice Hall, Inc. 145 container. add( printer. Event. Panel, Border. Layout. SOUTH ); All rights reserved. 146 container. add( button. Panel, Border. Layout. CENTER ); Outline

147 148 // set Rmi. Connector. Client reference 149 client = rmi. Client; 150 Start printing 151 // invoke method start. Printing of the via MBean 152 // Printer. Simulator MBean 153 try { 154 String name = client. get. Default. Domain() 155 + ": type=" + "Printer"; 156 object. Name = new Object. Name( name ); 157 client. invoke( object. Name, "start. Printing", 158 new Object[ 0 ], new String[ 0 ] ); 159 } 160 161 // invalid object name 162 catch ( Malformed. Object. Name. Exception exception ) { 3. 4 start printer 163 exception. print. Stack. Trace(); simulator 164 } 165 3. 5 get 166 // if cannot invoke the method Printer. Event. Handler 167 catch ( Reflection. Exception exception) { 168 exception. print. Stack. Trace(); 169 } 170 171 // if invoked method throws exception 172 catch ( MBean. Exception exception ) { 173 exception. print. Stack. Trace(); 174 } 175 176 // if MBean is not registered with MBean server 177 catch ( Instance. Not. Found. Exception exception ) { 178 exception. print. Stack. Trace(); 179 } Get Printer. Event. Handler 180 181 // instantiate Printer. Event. Notifier 2001 Prentice Hall, Inc. 182 Printer. Event. Handler printer. Event. Handler = All rights reserved. 183 new Printer. Event. Handler( client, this ); Outline

184 185 // unregister MBean when close the window 186 add. Window. Listener( 187 new Window. Adapter() { 188 public void window. Closing( Window. Event event ) 189 { 190 // unregister MBean 191 try { 192 193 // unregister the Printer. Simulator MBean 194 client. unregister. MBean( object. Name ); 195 196 // unregister the Printer. Event. Broadcaster 197 // MBean 198 String name = client. get. Default. Domain() 199 + ": type=" + "Printer. Event. Broadcaster"; 200 object. Name = new Object. Name( name ); 201 client. unregister. MBean( object. Name ); 202 } 203 204 // if invalid object name 205 catch ( Malformed. Object. Name. Exception exception) { 206 exception. print. Stack. Trace(); 207 } 208 209 // if exception is caught from method pre. Deregister 210 catch ( MBean. Registration. Exception exception ) { 211 exception. print. Stack. Trace(); 212 } 213 214 // if MBean is not registered with MBean server 215 catch ( Instance. Not. Found. Exception exception ) { 216 exception. print. Stack. Trace(); 217 } 218 Outline Unregister Mbeans when close window 3. 6 define actions when close window 2001 Prentice Hall, Inc. All rights reserved.

219 // terminate the program 220 System. exit( 0 ); 221 222 } // end method window. Closing 223 224 } // end Window. Adapter constructor 225 226 ); // end add. Window. Listener 227 228 } // end Printer. Management. GUI constructor 229 230 // out of paper events 231 public void out. Of. Paper() 232 { 233 Swing. Utilities. invoke. Later( 234 new Text. Appender( printer. Event. Text. Area, 235 " n. EVENT: Out of Paper!n" ) ); 236 } 237 238 // toner low events 239 public void low. Toner() 240 { 241 Swing. Utilities. invoke. Later( 242 new Text. Appender( printer. Event. Text. Area, 243 "n. EVENT: Toner Low!n" ) ); 244 } 245 246 // paper jam events 247 public void paper. Jam() 248 { 249 Swing. Utilities. invoke. Later( 250 new Text. Appender( printer. Event. Text. Area, 251 "n. EVENT: Paper Jam!n" ) ); 252 } Outline 4 display events in events panel Display events 2001 Prentice Hall, Inc. All rights reserved.

253 254 // add paper to the paper tray 255 public void add. Paper. Button. Action( Action. Event event ) 256 { 257 try { 258 client. invoke( object. Name, "replenish. Paper. Tray", 259 new Object[ 0 ], new String[ 0 ] ); 260 } 261 262 // if cannot invoke the method Add paper to paper try when 263 catch ( Reflection. Exception exception) 264 { click Add Paper button 265 exception. print. Stack. Trace(); 266 } 267 268 // if invoked method throws exception 269 catch ( MBean. Exception exception ) { 5. Add paper to 270 exception. print. Stack. Trace(); printer 271 } 272 6. Cancel pending 273 // if MBean is not registered with MBean server print jobs 274 catch ( Instance. Not. Found. Exception exception ) { 275 exception. print. Stack. Trace(); 276 } 277 Cancel pending print jobs 278 } // end method add. Paper. Button. Action 279 when click Cancel Pending 280 // cancel pending print jobs Print Jobs button 281 public void cancel. Pending. Print. Jobs. Button. Action ( 282 Action. Event event ) 283 { 284 try { 285 client. invoke( object. Name, "cancel. Pending. Print. Jobs", 286 new Object[ 0 ], new String[ 0 ] ); 287 } 2001 Prentice Hall, Inc. Outline All rights reserved.

Outline 288 289 // if cannot invoke the method 290 catch ( Reflection. Exception exception) 291 { 292 exception. print. Stack. Trace(); 293 } 294 295 // if invoked method throws exception 296 catch ( MBean. Exception exception ) { 297 exception. print. Stack. Trace(); 298 } 299 300 // if MBean is not registered with MBean server 301 catch ( Instance. Not. Found. Exception exception ) { 302 exception. print. Stack. Trace(); 303 } 7. Check printer’s 304 status 305 } // end method cancel. Pending. Print. Jobs. Button. Action 306 7. 1 get printer’s 307 public void check. Status. Button. Action ( Action. Event event ) status 308 { 309 Object online. Response = null; 310 Object paper. Jam. Response = null; Check printer’s status 311 Object printing. Response = null; when click Check 312 Object paper. Tray. Response = null; 313 Object pending. Print. Jobs. Response = null; Status button 314 315 // manage printer remotely 316 try { 317 318 // check if the printer is on line 319 online. Response = client. invoke( object. Name, 320 "is. Online", new Object[ 0 ], new String[ 0 ] ); 321 2001 Prentice Hall, Inc. All rights reserved.

322 // check if the printer is paper jammed 323 paper. Jam. Response = client. invoke( object. Name, 324 "is. Paper. Jam", new Object[ 0 ], new String[ 0 ] ); 325 326 // check if the printing is pringint 327 printing. Response = client. invoke( object. Name, 328 "is. Printing", new Object[ 0 ], new String[ 0 ] ); 329 330 // get the paper tray 331 paper. Tray. Response = client. invoke( object. Name, 332 "get. Paper. Tray", new Object[ 0 ], new String[ 0 ] ); 333 334 // get pending print jobs 335 pending. Print. Jobs. Response = client. invoke( object. Name, 336 "get. Pending. Print. Jobs" , new Object[ 0 ], 337 new String[ 0 ] ); 338 } 339 340 // if cannot invoke the method 341 catch ( Reflection. Exception exception ) { 342 exception. print. Stack. Trace(); 343 } 344 345 // if invoked method throws exception 346 catch ( MBean. Exception exception ) { 347 exception. print. Stack. Trace(); 348 } 349 350 // if MBean is not registered with MBean server 351 catch ( Instance. Not. Found. Exception exception ) { 352 exception. print. Stack. Trace(); 353 } 354 355 // status for the online condition 356 boolean is. Online = 357 ( ( Boolean ) online. Response ). boolean. Value(); Outline Check printer’s status by calling methods on Printer MBean 7. 2 prepare output 2001 Prentice Hall, Inc. All rights reserved.

358 359 // display status 360 if ( is. Online ) { 361 Swing. Utilities. invoke. Later( new Text. Appender( 362 printer. Status. Text. Area, 363 "n. Printer is ONLINE. n" ) ); 364 } 365 else { 366 Swing. Utilities. invoke. Later( new Text. Appender( 367 printer. Status. Text. Area, 368 "n. Printer is OFFLINE. n" ) ); 369 } 370 371 // status for the paper jam condition 372 boolean is. Paper. Jam = 373 ( ( Boolean ) paper. Jam. Response ). boolean. Value(); 374 375 // display status 376 if ( is. Paper. Jam ) { 377 Swing. Utilities. invoke. Later( new Text. Appender( 378 printer. Status. Text. Area, 379 "Paper jammed. n" ) ); 380 } 381 else { 382 Swing. Utilities. invoke. Later( new Text. Appender( 383 printer. Status. Text. Area, 384 "No Paper Jam. n" ) ); 385 } 386 387 // status for the printing condition 388 boolean is. Printing = 389 ( ( Boolean )printing. Response ). boolean. Value(); 390 Outline Append printer status to output area 7. 2 prepare output 2001 Prentice Hall, Inc. All rights reserved.

391 // display status 392 if ( is. Printing ) { 393 Swing. Utilities. invoke. Later( new Text. Appender( 394 printer. Status. Text. Area, 395 "Printer is currently printing. n" ) ); 396 } 397 else { 398 Swing. Utilities. invoke. Later( new Text. Appender( 399 printer. Status. Text. Area, 400 "Printer is not printing. n" ) ); 401 } 402 403 // status for paper tray condition 404 int paper. Remaining = 405 ( ( Integer )paper. Tray. Response ). int. Value(); 406 407 // display status 408 Swing. Utilities. invoke. Later( new Text. Appender( 409 printer. Status. Text. Area, 410 "Printer paper tray has " + paper. Remaining + 411 " pages remaining. n" ) ); 412 413 // status for pending print jobs 414 Object[] pending. Print. Jobs = 415 ( Object[] ) pending. Print. Jobs. Response ; 416 int pending. Print. Jobs. Number = pending. Print. Jobs. length; 417 418 // display status 419 Swing. Utilities. invoke. Later( new Text. Appender( 420 printer. Status. Text. Area, 421 "Number of pending print jobs: " + 422 pending. Print. Jobs. Number + "n" ) ); 423 424 425 } // end method check. Status. Button. Action 426 } Outline Append printer status to output area 7. 2 prepare output 2001 Prentice Hall, Inc. All rights reserved.

22. 3. 5 Compiling and Running the example • CLASSPATH – jdmkrt. jar and jdmktk. jar • Compile – Files in package com. deitel. advjhtp 1. jmx. Printer. Management – Files in package com. deitel. advjhtp 1. jmx. Printer. Simulator • Run – Printer. Management. Agent – Client. Printer. Management 2001 Prentice Hall, Inc. All rights reserved.

Outline Initial window Program output 2001 Prentice Hall, Inc. All rights reserved.

Outline Status after out-of-paper event happened Program output Out-of-paper event happened 2001 Prentice Hall, Inc. All rights reserved.

Outline Status after clicked Add Paper button Program output 2001 Prentice Hall, Inc. All rights reserved.

Outline Status after out-of-paper event happened Program output Out-of-paper event happened 2001 Prentice Hall, Inc. All rights reserved.

Outline Status after clicked Cancel Pending Print Jobs button Program output 2001 Prentice Hall, Inc. All rights reserved.